Benchmark: My reduce vs flatMap benchmark for collection

Script Preparation code:

var raw = new Array(250).fill({
    id: 'gid://something/Something/something',
    handle: 'something',
    name: 'Something',
    categories: ['SOMETHING'],
    lastViewedAt: '2022-03-18T21:30:18Z',
    isPinned: false,
});

Tests:

flatMap
const flatMapped = raw.flatMap(({ id, categories, handle, name, lastViewedAt, isPinned }) => { if (categories.length === 0) { return []; } return { category: categories[0], handle, url: "https://google.com/", name, lastViewedAt: lastViewedAt == null ? null : new Date(lastViewedAt), author: "someone", isPinned, type: "something", gid: id, }; });
reduce
const reduced = raw.reduce(function (array, { id, categories, handle, name, lastViewedAt, isPinned }) { if (categories.length === 0) { return array; } array.push({ category: categories[0], handle, url: "https://google.com/", name, lastViewedAt: lastViewedAt == null ? null : new Date(lastViewedAt), author: "someone", isPinned, type: "something", gid: id, }); return array; }, []);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
flatMap
reduce

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

**Benchmark Overview**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The provided benchmark involves two test cases: `reduce` and `flatMap`. Both tests are designed to measure the performance of these two methods on an array of objects.

**Test Cases**

The first test case, "flatMap", uses the `flatMap()` method to transform each element in the input array into a new array with the same length. The transformed array is then returned as the result of the benchmark.

The second test case, "reduce", uses the `reduce()` method to iterate over the input array and accumulate a value that represents the sum of all elements in the array. In this case, the accumulator is an empty array `[]`.

**Options Compared**

Two options are compared:

1. **flatMap()**: This method transforms each element in the input array into a new array with the same length.
2. **reduce()**: This method iterates over the input array and accumulates a value that represents the sum of all elements in the array.

**Pros and Cons**

* **flatMap()**:
	+ Pros: Can be faster for large arrays because it avoids the overhead of function calls and returns an array with the same length as the input.
	+ Cons: Can be slower for small arrays or when dealing with complex transformations due to the need to create a new array.
* **reduce()**:
	+ Pros: Can handle complex transformations and accumulates values that can be used for further processing.
	+ Cons: Can be slower than `flatMap()` for large arrays due to function call overhead.

**Library and Purpose**

In both test cases, no specific library is used. The `flatMap()` method is a native JavaScript method that uses the spread operator (`...`) under the hood, while the `reduce()` method is also a native JavaScript method.

**Special JS Feature or Syntax**

No special JS feature or syntax is used in these benchmark cases.

**Other Considerations**

When choosing between `flatMap()` and `reduce()`, consider the following:

* If you need to perform a simple transformation on each element, `flatMap()` might be a better choice.
* If you need to accumulate values from multiple elements, `reduce()` might be a better choice.
* If performance is critical for large arrays, consider using `flatMap()` or optimizing your code using techniques like memoization.

**Alternatives**

Other alternatives that can be used in place of `flatMap()` and `reduce()` include:

* **map()**: Similar to `flatMap()`, but returns an array with the same length as the input.
* **forEach()`: Iterates over each element in the input array, but does not accumulate values like `reduce()`.
* **Array.prototype.filter()`: Returns a new array with only elements that pass a test (like `categories.length > 0`).

Keep in mind that these alternatives may have different performance characteristics and use cases compared to `flatMap()` and `reduce()`.

Related benchmarks:

My reduce vs flatMap benchmark for collection (version: 0)

Comparing performance of: flatMap vs reduce

Created: 3 years ago by: Registered User

Jump to the latest result

flatMap

reduce

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):